I have just spent some time on the Earth Hour website. The message is: Uniting people to protect the planet. Apart from turning lights off during Earth Hour (an event that will be witnessed by ESA astronaut and WWF ambassador Andre Kuipers from the Space Station) there are challenges, games and information about the overuse of our planet resources.
One theme for children to explore is recycling. Why not try this interactive, multiple choice quiz on recycling with your children. Some of the answers may surprise you. The questions and answers are also available as pdf downloads on our quiz page.